U.S. patent number 5,662,624 [Application Number 08/307,750] was granted by the patent office on 1997-09-02 for heat dressing comprising a heat generating unit and an adhesive layer.
This patent grant is currently assigned to Coloplast A/S. Invention is credited to Peter Boman Samuelsen, Lars Sch.o slashed.nfeldt, Staffan Sundstrom.
United States Patent |
5,662,624 |
Sundstrom , et al. |
September 2, 1997 |
Heat dressing comprising a heat generating unit and an adhesive
layer
Abstract
A heat dressing for treatment of skin areas and comprising a
heat generating unit and a liquid-absorbing adhesive layer which
prior to use is coated with a strippable release layer. The
adhesive layer is preferably of a hydrocolloidal material and may
optionally contain one or more medicaments or be coated with
alginate fibre mats. The heat generating unit generates heat
preferably by means of galvanic or chemical energy, and the heat
dressing may further comprise elements for controlling the heat
development and/or the surface temperature.
Inventors: |
Sundstrom; Staffan
(Helsingborg, SE), Sch.o slashed.nfeldt; Lars
(Helsing.o slashed.r, DK), Samuelsen; Peter Boman
(Rungsted Kyst, DK) |
Assignee: |
Coloplast A/S
(DK)
|
Family
ID: |
8093199 |
Appl.
No.: |
08/307,750 |
Filed: |
September 26, 1994 |
PCT
Filed: |
March 26, 1993 |
PCT No.: |
PCT/DK93/00115 |
371
Date: |
September 26, 1994 |
102(e)
Date: |
September 26, 1994 |
PCT
Pub. No.: |
WO93/19706 |
PCT
Pub. Date: |
October 14, 1993 |
Foreign Application Priority Data
|
|
|
|
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Mar 27, 1992 [DK] |
|
|
0409/92 |
|
Current U.S.
Class: |
604/291; 602/2;
602/42; 602/43; 602/54; 602/57 |
Current CPC
Class: |
A61F
7/007 (20130101); A61F 7/034 (20130101); A61F
13/023 (20130101); A61L 15/18 (20130101); A61L
15/58 (20130101); A61L 15/58 (20130101); A61L
15/60 (20130101); A61F 2007/0071 (20130101); A61F
2007/0086 (20130101) |
Current International
Class: |
A61F
13/02 (20060101); A61L 15/16 (20060101); A61L
15/18 (20060101); A61L 15/58 (20060101); A61F
7/00 (20060101); A61F 005/00 () |
Field of
Search: |
;602/2,54,57,42,43
;604/113,114,291 ;600/2 |
References Cited
[Referenced By]
U.S. Patent Documents
Foreign Patent Documents
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|
|
|
|
|
0376490 |
|
Jul 1990 |
|
EP |
|
2722273 |
|
Nov 1978 |
|
DE |
|
3637978 |
|
May 1988 |
|
DE |
|
453565 |
|
Feb 1988 |
|
SE |
|
8905619 |
|
Jun 1989 |
|
WO |
|
Primary Examiner: Hafer; Robert A.
Assistant Examiner: Rodriguez; Cris L.
Attorney, Agent or Firm: Ostrolenk, Faber, Gerb &
Soffen, LLP
Claims
We claim:
1. A heat dressing, comprising a substantially planar heat
generating unit being coated on one side surface thereof with a
layer of liquid absorbing adhesive material which prior to use of
the bandage is coated with a strippable cover layer, characterized
in that the heat generating unit comprises metal powder, and that
the unit is so shaped that it is possible to bring the oxygen in
the air in contact with the said metal powder.
2. A heat dressing according to claim 1, characterized in that the
metal powder is a porous powder, and that the metal is selected
from iron, aluminium and magnesium.
3. A heat dressing according to claim 2, characterized in that the
heat generating unit further comprises fillers and moisteners.
Description
BACKGROUND OF THE INVENTION
The present invention relates to a self-adhesive heat dressing for
use in local treatment of skin and body areas.
Heat is widely used for treatment of minor nuisances, such as
infiltrations and muscular tensions.
In most cases, the heat treatment is capable of removing or
minimizing these nuisances by a relatively short treatment. Heat is
also used as an analgesic e.g. for menstrual pain. Heat treatment
is particularly important for treatment of rheumatism. Rheumatism
cannot be cured, but the heat treatment can ease the worst
pain.
Heat treatment has also been found to have significant effect for
reducing skin lesions, such as e.g. psoriasis plaques. An article
by Harukuni Urabe, MD, Keiko Mishitani, MD, Hiromu Konda, MD:
Hyperthermia in the Treatment of Psoriasis. Arch. Dermatol.--Vol.
117, December 1981, pp. 770-774, mentions an experiment in which
psoriasis has successfully been treated with heat. The treatment
lasted for 13-53 days. The heat dressing was changed 2-3 times a
day, and in each period the skin temperature was raised to between
42.degree. and 43.degree. C., which temperature was maintained for
more than 2 hours.
For many years it has been known that the temperature is of great
importance for regeneration of tissue, and thus also for the
healing process in a wound area. In particular, attention has been
given to the fact that a lowered temperature in a wounded area
causes reduced metabolism and consequently reduced wound-healing.
This is in complete agreement with the knowledge that when
transplanting tissue the greatest success is achieved when the
tissue graft has been cooled during the process. By cooling and
consequent reduced metabolism, the life time of the tissue is thus
increased.
Over the last few decades occlusive treatment of wounds has been
increasingly used, and everything indicates that within not to long
a time occlusive treatment of various kinds of wounds, such as
burns, operative wounds, bed sores, leg sores, and diabetic wounds,
will be the most commonly used method of treatment.
The great success of the occlusive method of treatment is largely
due to the moist wound environment, which a number of examinations
have shown i.e. causes an increased migration of epithelial cells.
More recent experiments have, however, shown that the isolating
effect of the occlusive method of treatment also plays an important
part for the wound-healing. By occlusive treatment, the treated
skin and wound areas are isolated, which may result in a slight
increase in the surface temperature of the skin and wound areas.
Thus, it is not an active heating, but only a shielding, whereby
the heat loss from the surface of the skin and wound areas is
minimized.
In spite of the fact that there is thus an indication that the
temperature in a wounded skin area has significant influence on the
healing process, and that by raising the temperature it is possible
to increase the speed of healing, use of sustained heat for local
treatment of wounds has as far as known not yet been used in
practice.
For such nuisances in body and skin areas which it is known to
treat with heat, the heat is usually applied by heat ray impact. It
is often a matter of heat treatment of larger body and skin areas,
but also local heat treatment is performed by means of heat
rays.
Treatment with heat rays can, however, only be performed within the
framework of hospitals or clinics, and is furthermore very
expensive both as regards equipment and staff costs.
Usually the heat treatment must be performed several hours daily to
obtain an efficacious effect. In particular when treating
rheumatism and, which has been found at a later date, when treating
wounds, a continuous treatment is required.
Thus, it is not only very expensive but also exacting on the
patients' patience each day to have to go through hours of
treatment with heat rays.
Another commonly known method of heat treatment is treatment with
heat bags or heat pads. This mode of treatment is used in
particular for minor nuisances, and the treatment is most
frequently prescribed by the patient himself.
Heat pads generally consist of a pad of synthetic material with
inlaid electric resistors in which the heat is generated by
connection to the mains. Heat pads are used most frequently for
menstrual pain and for milder forms of rheumatism. By treatment
with heat pad, the patient, as in the case of treatment with
radiation heat, is forced to sit or lie still for the duration of
the treatment.
Heat bags may also be electrically heated, but most often they are
chemically heated. The chemically heated heat bags consist of an
oxygen-permeable bag containing a metal powder which oxidizes upon
contact with oxygen, whereby heat is generated. Generally, metals,
such as iron, aluminium or magnesium, are used, and in particular
in the form of porous powders. The metal powders are usually mixed
with catalysts and assistants, such as chloride ions and active
carbon, as well as fillers and moisteners, such as bentonite and
cellulose compounds. Heat bags of this kind are well known, and
further mention hereof can be found e.g. in U.S. Pat. Nos.
4,282,005, 4,268,272, 4,106,478, 4,516,564, and 3,976, 046, and in
DE public disclosure No. 3 404 654 and DE patent specification No.
3 649 115.
The existing heat bags of the above type are especially used for
treatment of infiltrations and sports injuries and as heat
aggregate for people staying outdoors for quite a long time.
The heat bags are not particularly well-suited for use directly
against the skin, since the heat development can be difficult to
control. The skin is very heat-sensitive. Experiments with local
heating of the skin have thus shown that heating of a skin surface
area of 1 cm.sup.2 to a temperature of above 43.degree. C. for a
prolonged period can cause severe burns. The temperature is
especially critical in skin areas with impaired blood flow. The
skin temperature is by treatment with a heat bag furthermore
dependent not only on the amount of heat supplied, but also on the
skin's own temperature, blood flows in the skin area, and the
temperature of the surroundings.
Some of the known chemically heat generating heat bags are shaped
as plane dressings which essentially have the same thickness
throughout the entire extension of the dressing. This somewhat
alleviates the problem, since the heat generating metal powder in
such a heat dressing is evenly distributed over the entire area of
the dressing.
By further control of the air supply, chemically heat generating
dressings have thus been achieved which in one surface area of the
entire heat dressing essentially gives off a uniform amount of
heat.
In spite of a uniform heat emission, a heat dressing placed
directly against the skin can all the same give rise to local
superheating, and consequently burns on the skin.
As mentioned above there are several factors influencing the skin's
surface temperature by treatment with a heat dressing.
A particularly significant factor is the condition of the skin, and
in particular the blood flow in the areas is of great
importance.
A heat dressing having a surface area of e.g. 100 cm.sup.2 will
thus cover skin areas with essential differences in blood flow. In
the very local areas with a low blood flow, a heat agglomeration
can thus easily occur, so that the temperature in these areas
exceeds the average contact temperature of the heat dressing.
Patients with rheumatism are mostly older people whose blood flow,
in particular in the outer skin layers, is impaired. Similarly, the
blood flow in wounded skin areas, in particular in case of leg
sores, is often considerably reduced.
When treating such patients with a heat dressing, there is thus a
particularly large risk of local superheating of the skin, and
consequently risk of burns.
Another essential cause for local superheating is the poor or
defective contact between the heat dressing and the treated skin
surface, in particular if the treated surface is essentially
curved.
If the heat dressing is only in contact with the skin surface in
part of the surface area of the dressing, the heat is essentially
transferred to the skin surface area which is in contact. Since the
heat given off from the dressing is independent of the contact area
of the dressing, the skin surface area which is in contact will be
supplied with more heat than intended, whereby the area easily
becomes superheated.
In a treatment with a heat dressing, the dressing is usually placed
"loosely" on the area of treatment, which causes the patient great
nuisance since he must necessarily sit of lie still for the
duration of the heat treatment.
However, a few dressings are known which can be attached by means
of attaching bands. These dressings, however, can only be used for
treatment of skin areas on arms and legs, and furthermore the
attachment is not very stable, and the dressing is very liable to
get displaced or fall off completely when the patient moves.
EP patent application No. 376 490 discloses a heat dressing
consisting of a flat bag containing iron powder and water retaining
agents. One of the bag sides is air-permeable, and the other bag
side is provided with a thin layer of an acrylic adhesive which
enables the heat dressing to be attached to clothing or directly to
the skin surface.
Acrylic adhesives are normally considered skin-friendly adhesives
and are widely used for plasters and microporous tapes which are
moisture-penetrable. Heat dressings of the above type have,
however, been found to cause significant skin nuisances when placed
directly on the skin.
The heat dressing with acrylic adhesive causes in particular
substantial skin irritation in the form of itching, smarting, and
prickling in the skin surface, but by use of a heat dressing
provided with acrylic adhesive directly on the skin also pronounced
maceration, increased bacterial and fungal growth, and considerable
changes in the skin's pH-value will be noted.
As mentioned above, the heating of the skin causes significant
changes in the metabolic processes of the skin tissue. The changes
i.a. cause increased excretion of liquid and waste substances
through the skin, and the skin's sensitivity to exogenous impacts
is generally increased.
These factors presumably are the reason why positioning of the
dressing known from the EP patent application directly on the skin
causes the above skin nuisances.
DE public disclosure No. 3 434 292 discloses another self-adhesive
heat dressing which either on the entire surface facing the skin or
in an edge area is coated with an adhesive. However, nothing is
said about which adhesives may be used, and further it is stated as
patentable measure that the surface facing the skin is coated with
an analgesic. This analgesic may give further rise to the patient
getting burnt by the dressing, since the patient; because of the
skin's nerve endings being "unconscious" will not react as quickly
in case of a local superheating.
SUMMARY OF THE INVENTION
The object of the present invention is to devise a self-adhesive
heat dressing which does not suffer from the disadvantages
described above, and which thus essentially does not cause skin
irritation, increased bacterial or fungal growth, or significant
changes in the skin's pH-value.
The above object is achieved by the heat dressing according to the
invention which is of the kind, and which is characterized by the
adhesive material being liquid-absorbing.
DESCRIPTION OF THE INVENTION
It has thus surprisingly been found that a heat dressing which is
provided with a liquid absorbing adhesive in spite of the changed
metabolism of the skin tissue caused by the heat treatment does not
give rise to skin irritation and is further capable of preventing
increased bacterial or fungal growth, as well as significant
changes in the skin's pH-value.
Furthermore it has surprisingly been found that the heat dressing
according to the invention entails reduced risk of local
superheating and thereby reduced risk of burns on the skin surface,
since it has been found that liquid-absorbing adhesives have an
excellent heat distributing capacity, whereby local heat
agglomerations are avoided, and at the same time maceration of the
skin is essentially avoided.
It has further been found that the heat dressing according to the
invention by use for treatment of skin areas with reduced blood
flow, such as wounded skin areas, in particular leg sores and skin
areas on older people, in particular rheumatic patients, has
attained surprisingly good results.
The heat dressing according to the invention comprises, as
mentioned above, a preferably flat heat generating unit, one side
surface of which is coated with a liquid-absorbing adhesive, which
furthermore prior to use is coated with a strippable adhesive
layer.
The heat generating unit is capable of generating heat in any
suitable way. The heat can e.g. be generated by galvanic energy,
where electrically conducting foil or hot wires are inlaid in the
unit in an area-wise suitable embodiment, and where the energy is
supplied from batteries or from the mains via a transformer. The
hot Wires or the conducting foil may suitably be shielded from any
wound exudate e.g. by being laminated between two plastic films.
Furthermore, it is possible e.g. by means of a control circuit,
optionally with thermistor, to build in an effect/temperature
control so that an optimum temperature can be observed.
Another extremely suited method of generating heat is oxidation of
metal powder, which has been mentioned earlier in the
description.
Examples of other suited heat generating methods especially include
utilization of crystallization heat, decomposition heat, sulphide
oxidation, and reaction heat from cements.
The adhesive layer may be any liquid absorbing adhesive, e.g. a
hydrocolloidal adhesive or a hydrogel adhesive.
Hydrogel adhesives consist of a liquid-absorbing cross-linked
polymer, such as collagen, polyvinylalcohol, polyacrylate and
gelatine.
A hydrogel adhesive contains a large amount of water already before
it is used. In such cases where the adhesive is substantially
water-saturated, the adhesive is usually only negligently
self-adhesive, and must therefore be used in combination with
another adhesive, which is explained in more detail later in the
description. Other hydrogel adhesives with lower water content
exhibit excellent adhesive properties. Certain modified gellable
polymers are, however, capable of retaining a fairly good adhesive
capacity, even when essentially being water-saturated.
Hydrogel adhesives are described in e.g. EP public disclosure No.
97846 and No. 415183, SE published application No. 365 410, WO
public disclosure No. 88/6894 and U.S. Pat. No. 4,093,673.
Hydrocolloidal adhesives normally consist of
(i) a continuous phase containing an adhesive and e.g. being built
from an elastomer, an emollient for elastomers, a resin promoting
the adhesive capacity, and optionally an oil-based extender, as
well as an antioxidant, and
(ii) a discontinuous phase dispersed therein comprising
one or more water-soluble or water-swellable hydrocolloids, such as
starch derivatives or cellulose derivatives, or other adhophilic
polymers.
Such adhesive materials are e.g. known from DK patent
specifications No. 147 034 and No. 147 035 (corresponding to U.S.
Pat. Nos. 4,231,369 and 4,367,632). The adhesive materials herein
mentioned consist of
(I) a continuous phase comprising
(a) a physically cross-linked elastomer in the form of one or more
styrene-olefine-styrene block copolymers or ethylene-propylene
block copolymers,
(b) a hydrocarbon tackifier in the form of a polymer or copolymer
from cyclopentadiene, dicyclopentadiene, .alpha.-pinene and/or
.beta.-pinene,
(c) an antioxidant,
(d) optionally an oil extender in the form of one or more mineral
oils, and
(e) a polar emollient for the elastomer, such as e.g. an ester of a
polyethyleneglycol or polypropyleneglycol, or an ester of a di- or
poly-basic carboxylic acid with a preferably aliphatic alcohol,
and
(II) a phase dispersed in the continuous phase comprising one or
more water-swellable hydrocolloids.
Known liquid-absorbing adhesive materials may also contain other
elastomers, e.g. natural rubber, synthetic resins of similar nature
as natural rubber and silicone rubbers. As structure-forming
component in adhesive materials, use is also frequently made of
polyisobutylene of a suitable molecular weight distribution, e.g.
as stated in U.S. Pat. No. 3,339,546.
Other adhesive materials of similar nature are known from NO
published application No. 157 686, U.S. Pat. No. 4,867,748, and DK
patent specifications No. 154 806, No. 147 226, No. 157 899 and No.
154 747.
The adhesive material may further contain various medicaments,
since the heat dressing according to the invention has proved to be
extremely well-suited as transcutaneous dosing agent for dosing
various medicaments, such as hormones or nicotine.
Adhesive materials containing such medicaments have already been
mentioned in several of the above patent publications.
The adhesive layer may consist of two or more different adhesives
positioned in a pattern next to each other, in the way it is known
from DK published application No. 157 899. A low-adhering hydrogel
adhesive may very well be used in such a combination.
The adhesive layer may further be coated centrally with one or more
alginate fibre mats. Such a heat dressing according to the
invention with an alginate coated adhesive layer is primarily
intended for treatment of exudating wounds, and in use it must be
ensured that the alginate fibre mat does not have an extension
which is significantly larger than the wound area, since the
alginate coated skin area, if the alginate mat is dry, is not in
optimum contact with the heat dressing.
If in doubt whether the wound exudates sufficiently to cause rapid
moistening of the alginate mat, it is advisable to moisten the mat
by dripping thereon a sterile liquid prior to application of the
heat dressing.
To achieve good liquid capacity and good heat distribution
capacity, the adhesive layer must not be too thin. On the other
hand the adhesive layer must not be too thick either, since a
certain flexibility of the heat dressing is particularly
advantageous, especially when using the dressing on very curved
skin surfaces.
Thus the adhesive layer should preferably have a thickness of more
than 0.25 mm, and in particular between 0.5 and 2.0 mm.
The heat dressing according to the invention may furthermore on its
outer side (the side facing away from the skin) be provided with a
heat-reflecting foil, whereby the heat loss to the surroundings may
be reduced to a minimum.
Further, the heat dressing according to the invention may on its
outer side be provided with a layer of a polymeric foam. Such a
foam layer has both heat-insulating and pressure-alleviating
effects.
If the dressing according to the invention requires supply of air
for heat generation, it is in case of the last-mentioned measures
of course necessary to ensure that such air supply is not
hampered.
According to a special embodiment of the heat dressing according to
the invention, a liquid barrier is provided between the heat
generating unit and the liquid-absorbing adhesive layer. This
liquid barrier may e.g. be constituted by the inner side of the
heat generating unit, or a liquid-impermeable film may be
positioned between the liquid-absorbing adhesive layer and the heat
generating unit, which film is attached to the heat generating unit
by a secondary liquid-absorbing of non-liquid-absorbing
adhesive.
In this special embodiment of the heat dressing according to the
invention, the adhesive layer and the liquid-impermeable film may
have a larger surface area than the heat generating unit, so that
the adhesive and the liquid-impermeable film in the edge area of
the heat dressing are not in contact with the heat generating unit.
Heat dressings according to the invention of this type may suitably
have bevelled edges as known from DK published application No. 154
747.
The heat dressing according to the invention may further be so
shaped that the heat generating unit is replaceable, the adhesive
part consisting of an adhesive layer and a liquid-impermeable film
on its film side being provided with a coupling means which is
capable of retaining the heat generating unit in close contact with
the adhesive part for any desired duration. The coupling means may
e.g. by a film sheet being attached to the film side of the
adhesive part along three of its edges, so that the heat generating
unit may be introduced at the fourth and open edge and retained in
close contact with the adhesive part of the film sheet. If the heat
generating unit generates heat by chemical energy, it is preferred
that the film sheet is perforated.
Before use, the heat dressing according to the invention has on its
adhesive side been provided with a strippable cover layer.
If the heat dressing according to the invention generates its heat
by reaction with oxygen in the air, it must prior to use be packed
in an air-tight, non-oxygenous package. One of the inner surfaces
of this package may well constitute a strippable cover layer facing
the adhesive side.
BRIEF DESCRIPTION OF THE DRAWINGS
In the following, the invention is described in more detail,
reference being made to the drawings and the examples, in which
FIG. 1 is a side-view of an embodiment of the heat dressing, the
dressing being intersected at AA' (FIG. 2).
FIG. 2 is a top view of the dressing shown in FIG. 1.
FIG. 3a is a variant of the dressing shown in FIGS. 1 and 2.
FIG. 3b is the dressing shown in FIG. 3a in exploded state.
FIG. 4 is a side view of another embodiment of the heat dressing
according to the invention, the dressing being intersected at BB'
(FIG. 5).
FIG. 5 is a top view of the dressing shown in FIG. 4.
DETAILED DESCRIPTION OF THE DRAWINGS
The heat dressing according to the invention shown in FIGS. 1 and 2
consists of a liquid-absorbing adhesive layer (2), preferably a
hydrocolloidal adhesive layer, which is coated with a strippable
release layer (1), e.g. a paper layer, being surface treated with
silicone. On its other side the adhesive layer (2) is coated with a
liquid-impermeable film (3) consisting of e.g. polyurethane,
polyethylene, polybutadiene, polyvinylchloride,
polyvinylidenechloride, polyvinylalcohol, polyacrylate,
polysulphon, polystyrene, polypropylene, polyamide,
ethylene-vinylacetate-copolymer, polyester, polycarbonate,
polyvinylfluoride, copolyesterether, synthetic rubbers, silicone,
and mixtures thereof. Elastomers, such as polyurethane, polyester,
copolyesterether and synthetic rubbers, are particularly
preferred.
The film layer may further contain various additives, such as
anti-blocking agent, e.g. SiO.sub.2 and talc powder, emollients,
e.g. dioctyladipate, and fillers, and pigments.
A heat generating unit (8) is fixedly adhered on top of the film
layer by means of an adhesive layer (4). The adhesive layer (4) may
consist of any adhesive having a reasonable heat conducting
capacity and a reasonable adhesive capacity.
The heat generating unit (8) consists of a conducting foil-string
(6), preferably aluminium foil. For the sake of clarity the
conducting foil-string (6) is in FIG. 2 sketched so that there are
comparatively large spacings. The foil-string (6) may, if desired,
lie closer, since the position and closeness of the strings (6) are
chosen so that the surface of the heat dressing facing the skin
essentially gives off a uniform amount of heat across the entire
area of the surface.
The foil-string (6) is at either end connected to a conducting
wire. The two conducting wires are insulated and are connectable to
an energy source, such as a battery or the mains via transformer,
with a not shown thermostat-controlling unit, such as a control
circuit with PTC-thermistor, optionally being connected.
The foil-string (6) and the PTC-thermistor are encased by a film
layer (5,7) of e.g. polyurethane, polyethylene, polybutadiene,
polyvinylchloride, polyvinylidenechloride, polyvinylalcohol,
polyacrylate, polysulphon, polystyrene, polypropylene, polyamide,
ethylene-vinylacetate-copolymer, polyester, polycarbonate,
polyvinylfluoride, copolyesterether, synthetic rubbers, silicone,
and mixtures thereof. Elastomers, such as polyurethane, polyester,
copolyesterether and Synthetic rubbers, are particularly
preferred.
Further, the upper film layer (7) may suitably consist of or be
coated with a heat-reflecting material. The film layer (7) shown in
FIG. 2 is of a transparent material.
The two film layers (5,7) may be welded, fused or otherwise secured
to each other.
The heat dressing shown in FIGS. 3a and 3b is a variant of the heat
dressing according to the invention shown in FIGS. 1 and 2.
The adhesive layer (2) with the strippable release layer (1) and
the liquid-impermeable film (3) has a larger surface extension than
the heat Generating unit which consists of a conducting foil-string
(6) being coated with an upper and a lower film layer (7,5). The
adhesive part and the heat generating part are intersecured by an
adhesive layer (4) which has the same extension area-wise as the
heat generating part.
FIGS. 4 and 5 show a heat dressing according to the invention which
is heated by chemical energy. The adhesive layer (2), the
strippable cover layer (1) and the liquid-impermeable film (3)
correspond to like parts of the heat dressing according to the
invention shown in FIGS. 1-3.
The heat generating unit (19) consists of a first film layer (15)
which is attached to the liquid-impermeable film (3) by means of a
thin adhesive layer (4), and a second film layer (17) which along
the periphery of the heat unit and in two welding lines (18)
progressing transversely to the heat unit (19) is attached to the
film (15), so that the heat generating unit (19) is divided into
four bag sections containing metal powder (16) which by reaction
with the oxygen in the air is oxidized, whereby heat is developed.
The film layer (17) is suitably permeable for the oxygen in the
air, e.g. by perforations in the film layer (17). The two film
layers (15,17) may e.g. be selected from the same materials which
by way of example are stated for the films (3, 5, 7) in FIGS. 1-3.
The reaction speed is further adjusted by admixing various
additives in the metal powder, which has been discussed earlier in
the description.
EXAMPLE 1
A comparative examination of the wound-healing speed of leg sores
was performed using a non heat generating occlusive dressing and a
heat dressing according to the invention, respectively.
Dressing A: Comfeel.RTM. Ulcer Dressing, 10.times.10 cm.sup.2
having a thickness of approx. 1.1 mm (marketed by Coloplast
A/S).
Dressing B. Comfeel.RTM. Ulcer Dressing, 10.times.10 cm.sup.2
having a thickness of approx. 2.1 mm and on the film side of which
a heat unit had been attached by means of Micropore.RTM. tape
(marketed by 3M) along the edges Of the heat unit. The heat unit
was positioned centrally on the film, and its size was 5.times.5
cm.sup.2, and its capacity 15 mW/cm.sup.2 (equiv of
.DELTA.3.5.degree. C.).
Two groups of 5 patients with venous leg wounds were selected and
treated with dressing A and dressing B, respectively.
Comprilan.RTM. compress was used identically in both groups, which
as far as possible were quite comparable.
The dressings were changed 2-3 times a week, and the treatments
lasted for 3 weeks.
In the group which was treated with dressing B, an average weekly
area reduction of the wound of 15.3% was achieved as compared with
the control group of 7.2% over a period of 3 weeks. It was thus
evaluated that local heat supply via a dressing according to the
invention has a considerable healing-promoting effect on chronic
leg sores.
EXAMPLE 2
A patient having a large venous leg sore (55 cm.sup.2) was treated
with a heat dressing on one part of the wound to be controlled
against the other part.
In the experiment, the wound was by means of a vertically placed
brim of hydrocolloidal wound pasta (Comfeel.RTM. Pasta) divided
into in two equally large sections.
An experimental hydrogel wound dressing CP-DN19 was produced, which
consisted of a PVAL/PVP copolymer with a top film of polyurethane
(thickness 30 .mu.m), the size of its area being 10.times.10
cm.sup.2, and a heat unit having a surface area of 2.times.8 and
being supplied with a DC-voltage corresponding to an effect of 20
mW/cm.sup.2, which by means of Micropore.RTM. tape was attached to
the top film.
The heat unit was attached to the top film at a distance of 1 cm
from three of the edge sides of the dressings and at a distance of
6 cm from the fourth edge side. A line was drawn at a distance of 5
cm from the fourth edge side, so that the dressing was divided into
two halves, viz. half A without heat unit and half B with heat
unit.
The CP-DN19 dressing was placed over the entire wound including
pasta brim, so that the centre line precisely covered the pasta
brim. The CP-DN19 dressing was coated with a Comprilan.RTM.
compress. The treatment lasted for 14 days, during which the wound
was attended to regularly.
Granulation tissue formation was noted after 2-3 days on the part
of the Wound which was covered by dressing half B, and not until
after approx. 10 days on the part of the wound which was covered by
dressing half A.
After 14 days, the wound area under dressing half B had been
reduced by 28% versus merely 8% under dressing half A.
EXAMPLE 3
A heat dressing according to the invention was compared with a heat
dressing without liquid-absorbing properties, changes in the skin's
pH-value and Trans Epidermal Water Loss (TEWL) being observed.
Dressing A: This non-absorbing dressing consisted of a 60 .mu.m
thick saffron film, coated with a 30 .mu.m thick layer of
self-adhesive polyvinylether on one side and a heat dressing on the
other.
Dressing B: This absorbing dressing consisted of DuoDerm.RTM.
having a thickness of approx. 2.1 .mu.m (marketed by Convarec), a
heat unit being mounted on its film side.
Both dressings had an extension area-wise of 10.times.10 cm.sup.2,
of which the heat unit centrally covered an area of 5.times.5
cm.sup.2, being attached along its edge sides by Micropore.RTM.
tape. The heat unit had for both dressings an effect of 10
mW/cm.sup.2.
After 72 hours, skin pH and TEWL were analyzed by standard
methods.
______________________________________ Dressing pH g/m.sup.2 /h
TEWL ______________________________________ B 4.8 .+-. 0.6 7.2 .+-.
2.1 A 7.8 .+-. 0.8 21 .+-. 7
______________________________________
The absorbing dressing thus prevents moistening of the skin and
shift in pH (normal 5-6).
The experiment further showed that the volunteers for the test
complained of spot-wise strong heat and discomfort under the
non-absorbing dressing.
EXAMPLE 4
A heat dressing according to the invention was compared with a heat
dressing without liquid-absorbing properties by experiments on
rats.
Dressing A: This non-absorbing dressing consisted of an OpSite.RTM.
dressing having a thickness of about 60 .mu.m, a heat unit being
positioned on its film side.
Dressing B: This dressing according to the invention consisted of a
Comfeel.RTM. Ulcer Dressing having a thickness of about 1.1 mm, a
heat unit being positioned on its film side.
Both dressings had a size of 2.times.6 cm, and the heat unit was
centrally positioned and covered an area of 1.times.4, and being,
as in the previous examples, attached by Micropore.RTM. tape. The
heat units had an effect of 15 mW/cm.sup.2.
Two groups of 6 rats were wounded on their backs, and group 1 was
treated with dressing A, and group 2 was treated with dressing
B.
The treatment lasted for 10 days without change of dressing,
whereafter the test animals were killed and the healing
ascertained.
A significant difference in healing-speed between the two groups
was noted, wound size in % of initial wound excission being
determined at 11%.+-.6 in rat group 1, and 29% .+-.6 in rat group
2.
It is thus quite clear that dressing B according to the invention
results in a far quicker wound-healing than dressing A.
* * * * *